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LeechanX · Dec 15, 2014 · 753b1ad · 753b1ad
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diff --git a/Backtrack/01背包问题_递归.c b/Backtrack/01背包问题_递归.c
@@ -0,0 +1,58 @@
+#include <stdio.h>
+#define N 5
+#define M 20
+
+int maxvalue;
+int weighted;
+
+void display_outcome(int *answer,int *weight,int *value){
+	int i;
+	int myvalue=0,myweight=0;
+	for(i=0;i<N;i++)
+		if(answer[i]){
+			myvalue+=value[i];
+			myweight+=weight[i];
+		}
+	if(myvalue>maxvalue){
+		maxvalue=myvalue;
+		weighted=myweight;
+		for(int i=0;i<N;i++)
+			printf("%d",answer[i]);
+		printf("\n");
+	}
+}
+
+int condition(int *weight,int *answer,int step,int select){
+	int i;
+	int myweight=0;
+	for(i=0;i<step;i++)
+		if(answer[i])
+			myweight+=weight[i];
+	if(select)
+		myweight+=weight[step];
+	return myweight<=M;
+}
+
+void backtrack(int *weight,int *value,int *answer,int step){
+	if(step==N)
+		display_outcome(answer,weight,value);
+	else{
+		int i;
+		for(i=0;i<2;i++)
+			if(condition(weight,answer,step,i)){
+				answer[step]=i;
+				backtrack(weight,value,answer,step+1);
+			}
+	}
+}
+
+int main(int argc, char const *argv[])
+{
+	int weight[N]={3,4,5,6,7};
+	int value[N]={5,4,3,2,10};
+	int answer[N];
+	backtrack(weight,value,answer,0);
+	printf("maxvalue=%d\n",maxvalue);
+	printf("weighted=%d\n",weighted);
+	return 0;
+}
diff --git a/Backtrack/01背包问题_非递归.c b/Backtrack/01背包问题_非递归.c
@@ -0,0 +1,66 @@
+#include <stdio.h>
+#define N 5
+#define M 20
+
+int maxvalue;
+int weighted;
+
+void display_outcome(int *answer,int *weight,int *value){
+	int i;
+	int myvalue=0,myweight=0;
+	for(i=0;i<N;i++)
+		if(answer[i]){
+			myvalue+=value[i];
+			myweight+=weight[i];
+		}
+	if(myvalue>maxvalue){
+		maxvalue=myvalue;
+		weighted=myweight;
+		for(int i=0;i<N;i++)
+			printf("%d",answer[i]);
+		printf("\n");
+	}
+}
+
+int condition(int *weight,int *answer,int step,int select){
+	int i;
+	int myweight=0;
+	for(i=0;i<step;i++)
+		if(answer[i])
+			myweight+=weight[i];
+	if(select)
+		myweight+=weight[step];
+	return myweight<=M;
+}
+
+void backtrack(int *weight,int *value){
+	int answer[N];
+	int record[N];
+	int step=0;
+	record[step]=-1;
+	while(step>=0){
+		record[step]++;
+		while(record[step]<2 && !condition(weight,answer,step,record[step]))
+			record[step]++;
+		if(record[step]>=2)
+			step--;
+		else if(step==N-1){
+			answer[step]=record[step];
+			display_outcome(answer,weight,value);
+		}else{
+			answer[step]=record[step];
+			step++;
+			record[step]=-1;
+		}
+	}
+}
+
+int main(int argc, char const *argv[])
+{
+	int weight[N]={3,4,5,6,7};
+	int value[N]={5,4,3,2,10};
+	backtrack(weight,value);
+	printf("maxvalue=%d\n",maxvalue);
+	printf("weighted=%d\n",weighted);
+	return 0;
+}
diff --git a/Backtrack/ch7code/7.1.c b/Backtrack/ch7code/7.1.c
@@ -0,0 +1,167 @@
+#include <stdio.h>
+#include <stdlib.h>
+#define NODESIZE 7
+#define STARTNODE 0
+#define QSIZE 1000
+
+struct Node{
+    int vertex;
+    int height;
+    struct Node *prev;
+};
+
+struct Node *queue[QSIZE];
+int head,rear;
+int qempty(void){
+    return head==rear;
+}
+int qfull(void){
+    return head==(rear+1)%QSIZE;
+}
+void enqueue(struct Node *item){
+    queue[rear]=item;
+    rear=(rear+1)%QSIZE;
+}
+struct Node *dequeue(void){
+    struct Node *retval=queue[head];
+    head=(head+1)%QSIZE;
+    return retval;
+}
+
+int isneibor(int (*map)[NODESIZE],int node1,int node2){
+    return map[node1][node2];
+}
+
+void getneibors(int (*map)[NODESIZE],int node,int *neibors,int *size){
+    int counter=0,i;
+    for(i=0;i<NODESIZE;i++)
+        if(map[node][i])
+            neibors[counter++]=i;
+    *size=counter;
+}
+
+void displayoutcome(int *answer){
+    int i;
+    for(i=0;i<NODESIZE;i++)
+        printf("%d ", answer[i]);
+    printf("%d\n",STARTNODE );
+}
+
+int inme(struct Node *node,int who){
+    int ok=0;
+    while(node && !ok){
+        if(node->vertex==who)
+            ok=1;
+        node=node->prev;
+    }
+    return ok;
+}
+
+void displayout_come(struct Node *node){
+    printf("%d ",STARTNODE );
+    while(node){
+        printf("%d ",node->vertex );
+        node=node->prev;
+    }
+    printf("\n");
+}
+
+void bfs_search(int (*map)[NODESIZE]){
+    int i,step;
+    struct Node *currentnode=malloc(sizeof(struct Node));
+    currentnode->vertex=STARTNODE,currentnode->prev=NULL,currentnode->height=0;
+    enqueue(currentnode);
+    int neibors[NODESIZE],neiborsize;
+    struct Node *node;
+    while(!qempty()){
+        currentnode=dequeue();
+        step=currentnode->height;
+        if(step==NODESIZE-1 && isneibor(map,currentnode->vertex,STARTNODE)){
+            displayout_come(currentnode);
+            //break;
+        }
+        getneibors(map,currentnode->vertex,neibors,&neiborsize);
+        for(i=0;i<neiborsize;i++)
+            if(!inme(currentnode,neibors[i])){
+                node=malloc(sizeof(struct Node));
+                node->height=step+1,node->prev=currentnode,node->vertex=neibors[i];
+                enqueue(node);
+            }
+    }
+}
+#define STACKSIZE 100
+struct Node *stack[STACKSIZE];
+int sp=-1;
+int sempty(void){
+    return sp==-1;
+}
+void push(struct Node *item){
+    stack[++sp]=item;
+}
+struct Node *pop(void){
+    return stack[sp--];
+}
+struct Node *top(void){
+    return stack[sp];
+}
+
+void dfs_search(int (*map)[NODESIZE]){
+    struct Node *currentnode=malloc(sizeof(struct Node));
+    currentnode->vertex=STARTNODE,currentnode->height=0,currentnode->prev=NULL;
+    push(currentnode);
+    int neiborsize,neibors[NODESIZE],i;
+    struct Node *node;
+    while(!sempty()){
+        currentnode=top();
+        if(currentnode->height==NODESIZE-1 && isneibor(map,currentnode->vertex,STARTNODE)){
+            displayout_come(currentnode);
+            //break;
+        }
+        pop();
+        getneibors(map,currentnode->vertex,neibors,&neiborsize);
+        for(i=0;i<neiborsize;i++)
+            if(!inme(currentnode,neibors[i])){
+                node=malloc(sizeof(struct Node));
+                node->vertex=neibors[i],node->height=currentnode->height+1,node->prev=currentnode;
+                push(node);
+            }
+    }
+}
+
+void backtrace(int (*map)[NODESIZE],int *answer,int step,int *visited){
+    if(step==NODESIZE && isneibor(map,answer[step-1],STARTNODE)){
+        displayoutcome(answer);
+        return;
+    }
+    int myneibor[NODESIZE],neiborsize,currentnode=answer[step-1],i;
+    getneibors(map,currentnode,myneibor,&neiborsize);
+    for(i=0;i<neiborsize;i++)
+        if(!visited[myneibor[i]]){
+            answer[step]=myneibor[i];
+            visited[myneibor[i]]=1;
+            backtrace(map,answer,step+1,visited);
+            visited[myneibor[i]]=0;
+        }
+}
+
+int main(){
+    int map[NODESIZE][NODESIZE]={
+        {0,1,0,0,0,1,1},
+        {1,0,0,0,0,1,0},
+        {0,0,0,1,1,0,0},
+        {0,0,1,0,1,0,1},
+        {0,0,1,1,0,1,0},
+        {1,1,0,0,1,0,0},
+        {1,0,0,1,0,0,0}
+    };
+    int answer[NODESIZE];
+    answer[0]=STARTNODE;
+    int visited[NODESIZE]={};
+    visited[STARTNODE]=1;
+    printf("use backtrace:\n");
+    backtrace(map,answer,1,visited);
+    printf("use DFS:\n");
+    dfs_search(map);
+    printf("use BFS:\n");
+    bfs_search(map);
+}